package com.ks.utils;

import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.RSAPrivateKeySpec;
import java.security.spec.RSAPublicKeySpec;
import java.util.HashMap;

import javax.crypto.Cipher;

public class RSAUtil {
	/**globeStorage为为一位用户存储一个秘钥对，每个Ip对应一个秘钥对(为了测试方便每个用户生成一个)*/
//	public static ConcurrentHashMap<String, HashMap<String, Object>> globeStorage = new ConcurrentHashMap<String, HashMap<String, Object>>();
	public static HashMap<String, HashMap<String, Object>> globeStorage = new HashMap<String, HashMap<String, Object>>();
	/**
	 * 生成公钥和私钥,每次调用生成的秘钥不相同(模和私钥的指数不相同)
	 * 
	 * @throws NoSuchAlgorithmException
	 *
	 */
	public static HashMap<String, Object> getKeys() throws NoSuchAlgorithmException {
		HashMap<String, Object> map = new HashMap<String, Object>();
		/** 密钥生成器类用于生成公钥和私钥对 */
		KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA",
				new org.bouncycastle.jce.provider.BouncyCastleProvider());
		keyPairGen.initialize(1024);
		/**
		 * 秘钥生成器类生成秘钥对保存在KeyPair类中（KeyPairGenerator没有被显式初始化，那么对于生成的密钥的大小和其他（特定于算法的）值，将使用特定于提供者的默认值。）
		 */
		KeyPair keyPair = keyPairGen.generateKeyPair();
		RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
		RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
		map.put("public", publicKey);
		map.put("private", privateKey);
		return map;
	}

	/**
	 * 使用模和指数生成RSA公钥
	 *
	 *
	 * @param modulus  模
	 * @param exponent 指数
	 * @return
	 */
	public static RSAPublicKey getPublicKey(String modulus, String exponent) {
		try {
			/** 模和指数 */
			BigInteger b1 = new BigInteger(modulus);
			BigInteger b2 = new BigInteger(exponent);
			/**
			 * 密钥工厂用于将密钥(key类型的不透明密钥)转换成密钥规范(底层密钥密钥材料的透明表示),
			 * 反之亦然,密钥工厂是双向的,对于同一个密钥可以存在多个兼容的密钥规范 下面代码通过制定加密算法和提供者实例化一个KeyFactory
			 */
			KeyFactory keyFactory = KeyFactory.getInstance("RSA",
					new org.bouncycastle.jce.provider.BouncyCastleProvider());
			/** 根据指定的模和指数生成一个公钥 */
			RSAPublicKeySpec keySpec = new RSAPublicKeySpec(b1, b2);
			/** 秘钥工厂规范化公钥 */
			return (RSAPublicKey) keyFactory.generatePublic(keySpec);
		} catch (Exception e) {
			e.printStackTrace();
			return null;
		}
	}

	/**
	 * 使用模和指数生成RSA私钥
	 * 
	 * /None/NoPadding】
	 *
	 * @param modulus  模
	 * @param exponent 指数
	 * @return
	 */
	public static RSAPrivateKey getPrivateKey(String modulus, String exponent) {
		try {
			BigInteger b1 = new BigInteger(modulus);
			BigInteger b2 = new BigInteger(exponent);
			KeyFactory keyFactory = KeyFactory.getInstance("RSA",
					new org.bouncycastle.jce.provider.BouncyCastleProvider());
			RSAPrivateKeySpec keySpec = new RSAPrivateKeySpec(b1, b2);
			return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
		} catch (Exception e) {
			e.printStackTrace();
			return null;
		}
	}

	/**
	 * 公钥加密
	 *
	 * @param data
	 * @param publicKey
	 * @return
	 * @throws Exception
	 */
	public static String encryptByPublicKey(String data, RSAPublicKey publicKey) throws Exception {
		Cipher cipher = Cipher.getInstance("RSA", new org.bouncycastle.jce.provider.BouncyCastleProvider());
		cipher.init(Cipher.ENCRYPT_MODE, publicKey);
		// 模长
		int key_len = publicKey.getModulus().bitLength() / 8;
		// 加密数据长度 <= 模长-11
		String[] datas = splitString(data, key_len - 11);
		String mi = "";
		// 如果明文长度大于模长-11则要分组加密
		for (String s : datas) {
			mi += bcd2Str(cipher.doFinal(s.getBytes()));
		}
		return mi;
	}

	/**
	 * 私钥解密
	 *
	 * @param data
	 * @param privateKey
	 * @return
	 * @throws Exception
	 */
	public static String decryptByPrivateKey(String data, RSAPrivateKey privateKey) throws Exception {
		Cipher cipher = Cipher.getInstance("RSA", new org.bouncycastle.jce.provider.BouncyCastleProvider());
		cipher.init(Cipher.DECRYPT_MODE, privateKey);
		// 模长
		int key_len = privateKey.getModulus().bitLength() / 8;
		byte[] bytes = data.getBytes();
		byte[] bcd = ASCII_To_BCD(bytes, bytes.length);
		// System.err.println(bcd.length);
		// 如果密文长度大于模长则要分组解密
		String ming = "";
		byte[][] arrays = splitArray(bcd, key_len);
		for (byte[] arr : arrays) {
			ming += new String(cipher.doFinal(arr));
		}
		return ming;
	}

	/**
	 * ASCII码转BCD码
	 *
	 */
	public static byte[] ASCII_To_BCD(byte[] ascii, int asc_len) {
		byte[] bcd = new byte[asc_len / 2];
		int j = 0;
		for (int i = 0; i < (asc_len + 1) / 2; i++) {
			bcd[i] = asc_to_bcd(ascii[j++]);
			bcd[i] = (byte) (((j >= asc_len) ? 0x00 : asc_to_bcd(ascii[j++])) + (bcd[i] << 4));
		}
		return bcd;
	}

	public static byte asc_to_bcd(byte asc) {
		byte bcd;

		if ((asc >= '0') && (asc <= '9')) {
			bcd = (byte) (asc - '0');
		} else if ((asc >= 'A') && (asc <= 'F')) {
			bcd = (byte) (asc - 'A' + 10);
		} else if ((asc >= 'a') && (asc <= 'f')) {
			bcd = (byte) (asc - 'a' + 10);
		} else {
			bcd = (byte) (asc - 48);
		}
		return bcd;
	}

	/**
	 * BCD转字符串
	 */
	public static String bcd2Str(byte[] bytes) {
		char temp[] = new char[bytes.length * 2], val;

		for (int i = 0; i < bytes.length; i++) {
			val = (char) (((bytes[i] & 0xf0) >> 4) & 0x0f);
			temp[i * 2] = (char) (val > 9 ? val + 'A' - 10 : val + '0');

			val = (char) (bytes[i] & 0x0f);
			temp[i * 2 + 1] = (char) (val > 9 ? val + 'A' - 10 : val + '0');
		}
		return new String(temp);
	}

	/**
	 * 把字符串根据给定长度拆分成字符串数组<br />
	 * 例如：splitString("abcde", 2)->string["ab","cd","e"]
	 * 
	 * @param string 要拆分的字符串
	 * @param len    拆分的长度(拆分后数组每个字符串的长度)
	 * @return
	 */
	public static String[] splitString(String string, int len) {
		int x = string.length() / len;
		int y = string.length() % len;
		int z = 0;
		if (y != 0) {
			z = 1;
		}
		String[] strings = new String[x + z];
		String str = "";
		for (int i = 0; i < x + z; i++) {
			if (i == x + z - 1 && y != 0) {
				str = string.substring(i * len, i * len + y);
			} else {
				str = string.substring(i * len, i * len + len);
			}
			strings[i] = str;
		}
		return strings;
	}

	/**
	 * 根据指定长度拆分byte[]数组成二维byte[][]数组
	 * 
	 * @param data
	 * @param len
	 * @return
	 */
	public static byte[][] splitArray(byte[] data, int len) {
		int x = data.length / len;
		int y = data.length % len;
		int z = 0;
		if (y != 0) {
			z = 1;
		}
		byte[][] arrays = new byte[x + z][];
		byte[] arr;
		for (int i = 0; i < x + z; i++) {
			arr = new byte[len];
			if (i == x + z - 1 && y != 0) {
				System.arraycopy(data, i * len, arr, 0, y);
			} else {
				System.arraycopy(data, i * len, arr, 0, len);
			}
			arrays[i] = arr;
		}
		return arrays;
	}

	/**
	 * 获取公钥指数
	 * 
	 * @param request 公钥
	 * @return
	 */
//	public static Map<String, Object> getPublicKey(HttpServletRequest request) throws NoSuchAlgorithmException {
//		HashMap<String, Object> key;
//		Map<String, Object> map = new HashMap<String, Object>();
//		ConcurrentHashMap<String, HashMap<String, Object>> keyMap = GlobeStorage.globeStorage;
//		String ipAddr = SystemKit.getClientIP(request);
//		if (keyMap.containsKey(ipAddr)) {
//			key = keyMap.get(ipAddr);
//		} else {
//			key = RSAUtils.getKeys();
	/**    public static ConcurrentHashMap<String, HashMap<String, Object>> globeStorage = new ConcurrentHashMap<String, HashMap<String, Object>>();
	 * 	String 存储userip
	 * HashMap 存储公钥和私钥
	 * */
//			GlobeStorage.globeStorage.put(ipAddr, key);
//		}
//		RSAPublicKey publicKey = (RSAPublicKey) key.get("public");
//		String publicKeyExponent = publicKey.getPublicExponent().toString(16);
//		String publicKeyModulus = publicKey.getModulus().toString(16);
//		map.put("publicKeyExponent", publicKeyExponent);
//		map.put("publicKeyModulus", publicKeyModulus);
//		return map;
//	}

	public static void main(String[] args) throws Exception {

		HashMap<String, Object> map = getKeys();
		// 生成公钥和私钥
		RSAPublicKey publicKey = (RSAPublicKey) map.get("public");
		RSAPrivateKey privateKey = (RSAPrivateKey) map.get("private");
		System.out.println(publicKey.toString());
		// 模
		String modulus = publicKey.getModulus().toString();
		System.out.println("pubkey modulus=" + modulus);
		// 公钥指数
		String public_exponent = publicKey.getPublicExponent().toString();
		System.out.println("pubkey exponent=" + public_exponent);
		// 私钥指数
		String private_exponent = privateKey.getPrivateExponent().toString();
		System.out.println("private exponent=" + private_exponent);
		// 明文
		String ming = "1111234567890-9876s>_+{}:<>?-=[];',./!~gdfgcjkg";
		// 使用模和指数生成公钥和私钥
		RSAPublicKey pubKey = RSAUtil.getPublicKey(modulus, public_exponent);
		RSAPrivateKey priKey = RSAUtil.getPrivateKey(modulus, private_exponent);
		// 加密后的密文
		String mi = RSAUtil.encryptByPublicKey(ming, pubKey);
		System.err.println("mi=" + mi);
		// 解密后的明文
		String ming2 = RSAUtil.decryptByPrivateKey(mi, priKey);
		System.err.println("ming2=" + ming2);
		System.out.println(ming.equals(ming2));

//		Map<String, Object> keyMap = new HashMap<String, Object>();
//		keyMap = new RSAUtils().getKeys();
//		RSAPrivateKey privateKey = (RSAPrivateKey) keyMap.get("private");
//		System.out.println(privateKey);
//		RSAPublicKey publicKey = (RSAPublicKey) keyMap.get("public");
//		String ming = "abcdefg_+{}:<>?";
//		System.out.println("明文" + ming);
//		String mi = RSAUtils.encryptByPublicKey(ming, publicKey);
//		System.out.println("密文" + mi);
//
//		String ming2 = RSAUtils.decryptByPrivateKey(mi, privateKey);
//		System.out.println("解密明文" + ming2);
	}
}
